Human beings have been conscious of and concerned about the condition and appearance of their skin since the beginnings of recorded history. Skin which appears wrinkled, discolored, rough, flabby, or malformed gives an unwanted impression to others. Consequently, from the earliest times, various treatments and adornments have been employed to enhance the complexion one presents to the world.
A prime cause of skin wrinkling and roughness is dehydration of the scarf skin, especially the stratum corneum. Studies have shown that dryness and reduced flexibility of the stratum corneum can be corrected by rehydrating the skin, water being the only substance that will plasticize the stratum corneum effectively. Consequently, a number of skin care creams and lotions have appeared which contain agents to moisturize the skin.
The skin dehydration problem and the use of emollients to correct it are discussed in "Cosmetics--Science and Technology," Vol. 1, 2nd Ed., John Wiley & Sons, Inc., New York, NY, 1972, Ch. 2. The emollients used in skin care products include both film-forming materials which lubricate and coat the skin to passively impede evaporation of moisture and materials which are hygroscopic and actively attract moisture to the skin, i.e., humectants.
It is known that hydrocarbon, silicone and vegetable oils emolliate the skin, primarily by forming an occlusive film, a barrier to moisture loss. Skin care compositions containing such oils are disclosed, for example, in U.S. Pat. No. 4,488,564.
On the other hand, various polyhydric organic compounds, e.g., certain hydroxy-alcohols, esters, and amides, function primarily as humectants. Among the amides with known skin moisturizing abilities are various derivatives of gluconamide, as described, for example, in U.S. Pat. Nos. 3,766,267 and 3,855,290.
Mucopolysaccharides comprise another class of polyhydric organic compounds which may be employed as moisturizing agents in skin care compositions. More specifically, the use of hyaluronic acid or derivatives thereof in skin care compositions is disclosed in U.S. Pat. Nos. 4,303,676, 4,582,865 and 4,636,524, for example.
In addition to moisturizing agents of the sort described above, skin care formulations may contain various proteinaceous materials which are substantive to the skin and tend to smooth and soften the skin by becoming an integral part thereof or forming a film thereon. These materials include hydrolyzed animal protein, as disclosed in U.S. Pat. Nos. 4,416,873 and 4,482,537, for example. Protein having a vegetable origin can be used as well, oat flour being disclosed in U.S. Pat. No. 4,014,995.
Although the available skin care compositions may contain at least one skin moisturizing component and, perhaps, some protein, complete skin care requires attention to several additional problems, problems not satisfactorily addressed by the skin care compositions heretofore available. One of these problems is poor skin tone, i.e., sagging, flabby skin. The inclusion of a moisturizer and substantive protein in a skin care product may actually accentuate this condition, i.e., to the extent the product is taken up by the skin and leads to puffiness. Another problem is presented by the fact that benefits of using many of the known skin care preparations are short-lived; the emphasis is on treating a present skin condition, little attention being given to preventing the problem from soon recurring.
In addition, a number of the water-soluble materials useful as moisturizers are incompatible with candidate protein components, which makes it difficult to produce an attractive homogeneous product. This invention is directed toward solving the aforesaid problems.
Consequently, it is one object of this invention to provide skin care preparations which include both moisturizer and skin-structing protein, but which avoid incompatibility. It is another objective to provide preparations which also improve the tone and firm the skin. Yet another objective is to provide skin care products which are useful, not only for treating a present skin condition, but also to protect the skin against recurrence of the condition.